Motion picture projector



April 4, 1939. K; HOFFMANN MOTION PICTURE PROJECTOR Filed Jan. lO, 19382 Sheets-Shet 1 April 4, 1939. K. HOFFMANN 2,153,328

MOTION PTCTURE PRJECTOR Filed Jan. 10,1938 2 sheets-sheet 2 //llllllllill `Patented Apr. 4, 19139 PATENT cerise MOTION PICTURE:y PROJECTP?,

Kurt Hoffmann, Dresden, Germany, assigner te Zeiss IkonAktiengesellschaft, Dresden, @Ger-u mamy Application january 1d, 1938,Seriali No. 184,27 In Germany January 13, 1937 'l Claims.

The invention relates to improvements in mc-x tion picture projectors,and particularly is di-y rected to means for adjusting the motionpicture iilznY relatively to the picture window for bring- 5 ing thepicture frames on the film in correct alinement with said window. l

It is well known that after having threaded the nlm into the projectorand even during the operation ci the projector, it is frequentlynecessary i0 to adjust the film relatively to the picture WinddoW,because the picture frames on the lm move out oi registration with thepicture Window of the projector, owing to inaccuracies in the marginalapertures, film shrinkage, splicing irregularities and other reasons.

There have been proposed already various means for adjusting the filmand framing it correctly in the picture window whenever such anundesirable displacement of the picture occurs. One particular typeofsuch framing' devices is called central picture adjusting means. Alin aframing device of this particular type the drive wheel of the customaryGeneva gearing-which drive Wheel is provided with one tooth foradvancing the Geneva Wheel intermittently-As pivotally adjusted aboutthe axis of the Geneva Wheel, and thereby the film advancing' roller isadditionally rotated. During this additional roupon a pivotallyadjustment of the drive wheel oi the Geneva gearing about the axis oithe Geneva Wheel, the drive Wheel does not change its 'relae tiveposition with respect to the Geneva" wheel. in such a device it is thennot necessary to provide a special adjusting means for the shutter.

,Another object of the invention is to provide a picture framing deviceoiy simple and compact 5@ construction which may be positioned withinthe customary gear drive housing oi the projector. In accordance withthis object of the invention,7 the principal elements of the framingdevice are mounted concentrically about the axis oi the 1.

5d Crexieve'J wheel and any planetary gears as ein- (Cll. Sid-lil)ployed in the devices of pensed with. j

In the drawings:

Fig. 1 is a longitudinal sectional view oi the framing devicesubstantially along the line I--I of Fig. 3. l

Fig. 2 is a cross-sectional view of the Geneva gearing along the lineII-II of Fig. l,

Fig. 3 is a cross-sectional View along the line III- III of Fig l andFig. i illustrates a modiiication.

The Geneva gearing comprising a drive Wheel i anda Geneva wheel t ismounted in a casing i lled with oil. 'I'he drive Wheel i has a singletooth 2 for engaging the radial slots 5 of the Genevawheel 3 to rotatethe latter intermittently in well known manner. The shaft d on which theprior art are disthe drive wheel i is attached extends with both' endsoutwardly of the casing d. One end of the the other end carries a gearil engaging a driven gear 9 in a manner hereinafter described.

The casing d is provided with a tubular en tension lil extendingparallel to the shaft The tubular extension i0 is rotatably supported ina bearing sleeve li which is iixedly attached at its outer end by meansof a flange l2 to a wall of the gear housing of the projector asindicated at lll. A. pin ida on the tubular extension pro jects into acircumferentially extending slot Sie in the bearing sleeve it andprevents an amai displacement of the extension it. A shaft iti isrotatably mounted in the bore of the tubular exm tension it. One end ofthe shaft iii projects into the housing i and has the Geneva wheelsecured thereto. The other end of the shaft iti projects from the `outerend of the tubular extension l@ and has a film sprocket i6 attachedthereto which is 'intermittently rotated by said Geneva wheel The outercircumference of the tubular extension l0 is provided with a helicalgroove i8 for a slide block I9 which has attached. thereto a pin 2liextending radially outwardly through an axial slot 2i arranged in thestationary bearing sleeve il. The outer end of the pin 20 is connectedwith another slide block 22 which is mounted in an annular groove 23 cutinto the inner wall of a threaded sleeve 2li which surrounds the outercircumference of the bearing sleeve li. 'I'he sleeve 2li is providedwith an iriterior thread 25 and an oppositely directed eirengaging thegear 6 on the.shaft 6. The gear 9 by means of a cylindrical hub portion39 is `rotatably mounted on the stationary bearing sleeve II and issecured against axial displacement by a shoulder 3I on said sleeve IIand a collar 32. The outer circumference of the hub is provided with athread 33 engaging the interior thread 25 of the sleeve 24. The gear 9is also provided with an overhanging portion providing a deep annularrecess surrounding the threaded hub 30. The outer wall of this annularrecess is provided with an interior thread 36 which rotatably engages anexterior thread on the hub 36 of a spur gear 31. The bore of this spurgear 31 is provided with an interior thread 39 engaging the exteriorthread 26 of the sleeve 24.

'Ihe spur gear 31 is driven by a gear 39 which in turn is driven by thedrving mechanism (not shown) of the projector, for instance an electricmotor. threaded connections with the gear 9 and sleeve 24 respectivelydrives these members and also engages with its teeth a gear 40 on a stubshaft 4I. The gear 40 in turn engages a gear 42 on a shaft 43 whichoperates the shutter 44 of the projector.

The shutter 44 may be of any desired or conventional type and in thepresent instance a rotary drum shutter having ,two shutter blades 45 foralternately covering the picture window indicated at 46 is employed.

A worm gear segment 48 is attached to the casing 4 of the Geneva gearingwith the center of its curvature coinciding with the axis of the shaftI5 on which the Geneva wheel 3 is mounted.

`A worm 49 engaging said worm segment 46 is mounted lon a shaft 5Dextending outwardly of the gear housing of the projector and hasattached to its outer end a knob 5I for manually rotating said worm 49.

The operation' of the picture adjusting device of, the present inventionis as follows:

If, after threading the film into the projector,

or during the operation of the projector the'picture is not correctlyframed, the operator has to rotate the knob 5l to bring about anadjustment of the picture in the picture window. The rotation of theknob 5I and the worm 49 connected therewith results in a rotativeadjustment of the casing 4 about the axis of the Geneva wheel 3.

During this rotative adjustment off the casing 4 the drive wheel Imounted in the same is moved with its axis of rotation in an arcute pathabout the axis of the Geneva wheel 3. The tubular ex- `tension I9 whichis fixedly connected to the casing 4 is likewise rotated. The helicalgroove I6 of the tubular extension I 0 will be moved relatively to theslide block I9 and the pin 29 attached thereto. Since the bearing sleeveIl is stationary the pin 20 will be forced to move axially along theslot 2| and due to its connection with the slide block 22 in the annulargroove 23 the pin 29 will transmit to the threaded sleeve 24 an axialmovement. The threads 25 and 26 on the sleeve 24 have a suitable pitchwhich upon the application of a force tending to move the sleeve inaxial direction causes the threads 25 and 26 to screw intothetwo gears 9and 31 respectively. Since now the threads 25 and 26 are oppositelythreaded and the two gears 9 and 31 are rotatably connected with eachother by the ythread 36, which has a very lowpiksh compared with thepitch of the threads 25 and 26, the gear 31, however, due to itsengagement with the gear 39 remains relatively speaking stationary, onlyThe spur gear 31 by means of itsz thegear 9 will be rotatively adjusted.`Since now the gear 9 during the rotative adjustment of the drive wheelI about the axis of the Geneva wheel 3 is rotated the same distance,owing to its engagement with the gear-f6 on the shaft 6 which carriesthe drive Wheel I, the gear 6 cannot roll along the teeth 26 of gear 9and therefore an additional rotation of the shaft 6 around its own axisdoes not occur when the shaft 6 is adjusted in an arcuate path about theGeneva wheel shaft I5. Accordingly the synchronism between the drivewheel I and the shutter blades 45 is maintained.

During each adjustment of the knob 5l, vhowever, the casing 4 is rockedabout the axis of the shaft I5 and the next engagementof the pin 2 witha slot 5 of the Geneva wheel 3 will transmit to the latter and the shaftI5 and the film sprocket I6 attached thereto a supplemental rotationwhich may be negative or positive with respect to the normal drivingdirection of the sprocket, so `that the film is adjusted relatively tothe picture window 46. In this manner the knob 5I may be manipulateduntil the picture is correctly framed. The arrangement of the twooppositely directed threads 25 and 26 on the sleeve 24 has the advantagethat the axial displacement of the sleeve and accordingly the length ofthe sleeve is reduced to one half. It is, however, also possible toprovide the sleeve only with a single thread and to use another type ofguide for insuring an axial displacement of the sleeve. In such a case,the axial displacement would have to be twice as long in order to obtainthe same result obtained with two oppositely directed threads. In Fig. 4which illustrates such a modification the sleeve 24 is only providedwith its interior thread 25, while its outer circumference is providedwith an axially extending groove '52 for slidably receiving a key 54attached to the inner wall of the bore of the spur gear 31.

What I claim. is:

1'. In a motion picture projector having a picture Window, thecombination with a rotary shutter and a film sprocket secured at one endof a shaft at the other end of which is secured a Geneva Wheel drivenintermittently by a continuously rotating drive wheel, of a picturefram-` ing means comprising a manually adjustable member for adjustingthe axis of said drive wheel about the axis of said Geneva wheel andthus transmitting an additional rotative `move-- ment to said filmsprocket for moving the film relatively to the picture window, means fordriving said drive wheel and said rotary shutter, said means including agear rotatable about the axis of said shaft and arranged between saidfilm sprocket and said Geneva wheel and meshing with a pinion, asecondshaft on which said pinion and said drive wheel are secured, said meansincluding also a transmission between said gear and said shutter. andmeans actuated by said manually adjustable member for rotatablyadjusting said gear relatively to said transmission about the axis ofsaid Geneva wheel the same amount the said drive wheel is adjusted bysaid manually adjustable member so that the relative position betweensaid drive wheel and said shutter remains unchanged.

2. In a motionmpicture projector having a plcture window,l thecombination with a rotary shutter and a lm sprocket operatedintermittently by` a Geneva wheel driven by a continuously rotatingdrive wheel, of a picture framing means comprising a manually adjustablemember for' an additional rotative movement to said lm sprocket formoving the film relatively to the picture window, means for driving saiddrive wheel and said rotary shutter, said means including' a gearrotatable about the axis of said Geneva wheel and meshing with a pinion,a shaft on which said pinion and said drive wheel are secured, saidmeans including also a driven spur gear coaxially with said gear androtatably coupled with the same by a thread and by a transmission withsaid rotary shutter, and an axially adjustable sleeve operativelyconnected with said driven spur gear and said gear meshing with saidpinion, and means for axially displacing said sleeve whenever saidmanually adjustable member is actuated about a distance which causes arotative adjustment of said gear about the axis of said Geneva wheel thesame amount the said drive wheel is adjusted by said manually adjustablemember so that the relative position between said drive-wheel and saidshutter remains the same..

it, In a motion picture projector having a picture window, thecombination with a rotary shutter and a lm sprocket operatedintermittently by a Geneva wheel driven -by a continuously rotatiuedrive wheeLof a picture framing means comprising a manually adjustablemember for adjusting the axis of said drive wheel about the axis of saidGeneva wheel and thus transmitting an additional rotative movement tosaid lrn sprocket for moving the nlm relatively to the picture window,means for driving said drive wheel and said rotary shutter, said meansincluding a gear rotatable about the axis of said Geneva wheel andmeshing with a pinion, a shaft on which said pinion and said drive wheelare secured, said means including also a driven spur gear rotatablycoupled with said gear by a thread and over a transmission with saidrotary shutter, and an axially displaoeable threaded sleeve in threadedconnection with said spur gear and also with 'said gear meshing withsaid pinion, and means for axially displacing said sleeve whenever saidmanually adjustable member is actuated, about a distance which causes arotative adjustment of said gear about the axis of said Geneva wheel thesame amountthe said drive Wheel is adjusted by'said manually adjustablemember so that the relative position between said drive wheel and saidshutter remains the same.

d. ln a motion picture projector having a picture window, thecombination with a rotary shutu ter .and a film sprocket operatedintermittently by a Geneva wheel driven by a continuously rotating drivewheel, or a picture framing means comprising a manually adjustablemember for adjusting the axis of vsaid driveiayheel about the ams oisaid Geneva wheel and thus transmitting an additional rotative movementto said nlm sprocket for moving the nlm relatively to the pic-1 turewindow', means for driving said drive wheel and said rotary shutter,said means including a gear rotatable about the axis oi` said Genevawheel and meshing with a pinion, a shaft on which said pinion and saiddrive wheel are secured, said means including also a driven spur gear inaxial alinement with said gear, and rotatably coupled with the same by athread and over a transmission with said rotary shutter, and anaxiallvdisplaceable sleeve provided with an interior thread and anexterior thread opposed to each other, said interior thread engag-a inga corresponding exterior thread on the hub of said gear, while theexterior thread of said sleeve engages a corresponding interior threadon said spur gearl and means for axially displacing said sleeve wheneversaid manually adjust= able member is actuated about a distance whichcauses a rotative adjustment of said gear about theaxis'of said Genevawheel the same amount the said drive Wheel is adjusted bysaid manu allyadjustable member so that the relative po sition between said drivewheel and said shutter u remains the saineo wheel, of a picture framingmeans including a housing in which said drive wheel and said neva wheelare mounted, a tubular extension supported in a stationary bearingsleeve, a shaft rotatably supported in said tubular extension and havingsaid Geneva wheel and said film sprocket fixedly mounted thereon, amanually operable member tork pivotally adjusting said housing about theaxis of said shaft whereby the axis of said drivewheel is adjusted aboutthe axis ot said Geneva wheel for transmitting an additional rotativemovement to said iilm sprocket and thus moving the iilm relativelyto thepicturewindow ci the projector, means for driving said drive wheel andsaid rotary shutter, said means including a gear rotatable about theaxis of said Geneva wheel and meshing with a pinion, a shaft on whichsaid pinion and said drive wheel are se1 cured, said means includingalso a transmission between said gear and said shutter, and meansoperatively connected with said tubular extension for adjusting saidgear about the axis oi said Geneva wheel the same amount to which saiddrive wheel is adjusted bysaid manually adjustable member formaintaining the relative position between said drive wheel and saidshutter.

6. in a motion picture projector having a pic-= ture window, thecombination with a rotary shut= ter and a film sprocket operated by aGeneva wheel drivenL by a` continuously rotating drive wheel, oi apicture framing means including a housing in which said drive wheel andsaid.

Geneva wheel are mounted, a tubular extension ing said drive wheel andsaid rotary shutter, saidA means including a gear rotatably mounted onsaid bearing sleeve and meshing with a pinion coaxiallyfdxed to saiddrive wheel, said means including also a driven spur gear rotatably coupled by means oi-'a thread with said gear and by a transmission withsaid rotary shutter, an axially adjustable sleeve mounted on saidbearing sleeve and in threaded connection with said spur gear and thegear meshing with said pina ioni and means for axially displacing saidsleeve whenever said manually adjustable member is actuated about adistance which causes a row' vedy connected with said housing androtatably- ,10 jecting with one end into an interior annular groove orsaid sleeve and with its other end into a helical groove in the outercircumference of the tubular extension of saidnhousing, said stationarybearing sleeve being provided with a lengthwise extending slot forpermitting the passage of said pin and guiding its linear movement whensaid housing and therewith said tubular extension is rotatably adjustedby saidmanually opi erable member.

KURT HOFMANN,

